Automatic ink supply and refill systems for ink jet printers are also well known. Automatic ink supply and refill systems can be classified either as passive refill systems, which rely on gravitational or pressure differentials to cause the ink to flow through the system, or active systems, which use a pump or mechanical assist to move the ink through the system.
Active ink refill systems have been used with either a continuous ink supply system, such as described in U.S. Pat. Nos. 4,399,466, 4,462,037 and 4,680,696, or an on-demand ink supply system, such as described in U.S. Pat. Nos. 4,074,284 and 4,432,005, the subject matter of each of which is herein incorporated by reference in its entirety. These active ink refill systems rely on atmospheric or positive pressure hydrodynamic conditions to supply ink to the print nozzles.
Passive ink refill systems use gravity to feed ink. In one example, described in U.S. Pat. No. 4,959,667, the subject matter of which is herein incorporated by reference in its entirety, the system is controlled by a three-way valve to feed ink from an ink reservoir to an ink supply container as part of a single replaceable unit that is carried by the print carriage. The drawback to this system is that when the print heads are printing on large media, print head performance may be greatly diminished if the weight and volume of the large reservoir of ink needs to be supported by the print carriage as it traversed across the print medium.
To overcome the drawback of supporting a large reservoir of ink on the print carriage, many prior art ink delivery systems involve a service station which refills the ink jet cartridge only when the print carriage is at one or the other end of the print axis so that the ink jet cartridges can be docked with the service station. Once docked, the ink reservoir in the ink jet cartridge is quickly refilled and the print carriage is allowed to return to its printing operation. Various examples of service station-type ink refill systems for ink jet cartridges are shown in U.S. Pat. Nos. 3,967,286, 4,831,389, 4,967,207, 4,968,998, 4,999,652 and 5,136,305, the subject matter of each of which is herein incorporated by reference in its entirety.
There are two basic problems with service station-type ink refill systems. First, the print speed of the ink jet printer is decreased by the time required to perform the docking and refill operation. Second, in order to minimize the time of the docking and refill operation, the ink is quickly transferred to the ink jet cartridge at a pressure that typically exceeds the nominal hydrodynamic properties of the ink jet cartridge. As a result, there may be leaking or weeping of the print heads during the refill operation, resulting in poor print quality.
U.S. Pat. No. 6,164,766 to Erickson, the subject matter of which is herein incorporated by reference in its entirety, describes an ink delivery system for an ink jet printer that includes an ink jet cartridge removably mountable in the print carriage and constructed as a self-contained unit that includes a print head and an ink supply container that stores a first quantity of liquid ink at a given negative pressure hydrodynamic condition. An ink reservoir external to the print carriage stores a second quantity of ink for replenishing the first quantity of ink in the ink supply container. The external ink reservoir is coupled to the ink supply container in the ink jet cartridge to supply ink from the second quantity of ink to the first quantity of ink during operation of the ink jet printer as the print carriage traverses across the print medium.
While the improved ink delivery system of Erickson no longer requires a service station assembly, the drawback to this system is that it requires that each printer cartridge be separately connected to, and refilled from, the external ink reservoir (or reservoirs). In addition, the ink level in each individual cartridge is separately monitored.
As is readily seen, there remains a need in the art for an improved ink delivery system that solves the problems of the prior art.
The present invention comprises an improved fluid delivery system comprising a plurality of intercoupled cartridge assembles. Each cartridge assembly comprises a plurality of interconnected cartridges, each interconnected cartridge comprising a reservoir for holding a jetting fluid, wherein the reservoir is operatively connected to an ink jet print head. Each cartridge assembly is interconnected by a first interconnection assembly and a second interconnection assembly. The first interconnection assembly maintains the plurality of interconnected cartridges at a negative pressure. The second interconnection assembly maintains at least an essentially equal level of the jetting fluid within each of the reservoirs of the plurality of fluid cartridges. In the improved fluid delivery system of the invention, the jetting fluid is replenished in the plurality of interconnected cartridges by replenishing jetting fluid in a selected cartridge. The second interconnection assembly is used to distribute the jetting fluid among the reservoirs of the interconnected cartridges. A sensor is coupled to the selected reservoir to monitor the level of jetting fluid in the cartridge assembly.